import { Transform } from 'node:stream'

class JSONParser extends Transform {
  constructor(options = {}) {
    super({ readableObjectMode: true })
    this.chunks = []
    this.globalOptions = { ...options }
  }

  _transform(chunk, encoding, callback) {
    this.chunks.push(String(chunk)) // todo consider using a string decoder
    callback()
  }

  _flush(callback) {
    try {
      const fields = JSON.parse(this.chunks.join(''))
      this.push(fields)
    } catch(e) {
      callback(e)
      return
    }
    this.chunks = null
    callback()
  }
}

export default JSONParser
